The answer may surprise you
Some premium paint grades are thicker than contractor or builder-grade paint. These higher grades of paint may therefore give a little more latitude for changing colors with just one coat. See Ask the Painter: Paint is Paint, Right?
But how do you know when two (or more) coats are required? As with most painting questions, the answers is “It depends”. Factors such as the new color, existing color and sheen, grade of paint to be used, and application method all have a bearing on how many coats of paint are required to achieve the desired results. Let’s briefely examine each of these factors.
A common misconception is that darker colors will cover, or “hide” an underlying color better than lighter ones. This is a natural assumption, given that if you want to hide something in a document you use a marker to “black it out”. But with paint, just the opposite is true. Darker colors are mixed in a paint “base” that is more translucent than lighter colors. Consider the following analogy. A glass of cola is dark brown, but you can shine a light through it. Now take a glass of milk and pour a little cola into it and stir. The result is a light brown colored mixture, but because of all the solids in the milk, you cannot shine a light through it. Darker colored paints have less “body” and therefore take two or more coats. In the case of a third coat, this is usually in the form of a “foundation” primer that lets the color develop properly. Red colors, for example, often are painted using two color top-coats over a gray primer coat.
Existing color, or more precisely, the difference between the existing color and the new color is another consideration. If the new color is “close” to the existing color, then generally only one coat is needed, even in the case of darker colors. Creating a substantial color change, or painting over white usually requires a second coat to prevent the underlying color from “peeking through”.
If the existing paint has much sheen to it (i.e. its is satin, semi-gloss, or even full gloss), then the first coat of the new paint may “slide” leaving streaks that require a second coat to cover properly. The sheen of a paint is determined by how smooth it is on the surface. The more sheen the paint has, the smoother its surface is. The new paint may not be able to “bite” into the smoother surface and may then be carried away by the brush or roller leaving a streak.
The grade of new paint being used has a bearing two ways: thickness of the paint film left after the “carrier solvent” — water in the case of latex paints — evaporates, and volume of solids in the paint. Paints with a higher volume of solids and/or that leave a greater film thickness simply deposit more material to hide the underlying color. As discussed last month, premium grade paints have higher volumes of solids than lesser grade paints, so spending a few more dollars on paint might mean the difference of not needing a second coat.
Lastly, application method has a bearing on how many coats are required. Brushes tend to push paint away from them, leaving brush streaks that may need a second coat to cover. Rollers can rapidly apply a lot of paint to a surface, but to a certain extent, they are also pushing paint away. Rolling paint onto a surface with a satin or higher sheen will probably illustrate the “sliding” problem mentioned above. Spraying a surface is a great way to apply a uniform coat of paint without the streaking or sliding that comes from methods that push paint around and require some “bite” into the existing surface. But spraying is not well suited for non-solid surfaces (e.g. wrought iron fences or lattice work), and is generally not the preferred method interior repaint work. It also requires specialized equipment and skills.
When planning your next paint project, consider the factors mentioned above when planning the work. Southern Painting Estimators are well-versed in all of these considerations and will quote the approach that will yield the best results and will be happy to explain their recommendation.
Copyright 2009 Jeff Stec
As an expert in the field of painting, with years of hands-on experience and a deep understanding of the nuances involved, I can attest to the importance of selecting the right paint and applying it correctly to achieve optimal results. My expertise is not only grounded in theoretical knowledge but also in practical applications, having worked on numerous painting projects ranging from residential to commercial settings.
The article touches upon several key concepts related to the application of paint, and I'll provide detailed insights into each of them:
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Paint Grades and Thickness: The article mentions that some premium paint grades are thicker than contractor or builder-grade paint. This thickness plays a crucial role in achieving coverage, especially when changing colors. Premium paints, with their increased thickness, often allow for better coverage in a single coat. The evidence for this lies in the composition of these paints, which typically contain higher volumes of solids.
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Factors Influencing the Number of Coats: The article rightly emphasizes that the number of coats required depends on various factors. These include the new color, existing color and sheen, grade of paint, and the application method. This demonstrates a comprehensive understanding of the multifaceted nature of painting projects.
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Darker Colors and Translucency: The article dispels the misconception that darker colors provide better coverage. In fact, it explains that darker colors are often mixed in a more translucent paint base than lighter colors. This is a nuanced understanding of color mixing and translucency, supported by the analogy of a glass of cola versus a glass of milk.
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Existing Color and Color Difference: The article highlights the importance of considering the existing color and the difference between the existing and new colors. A minimal color change may require only one coat, while a substantial change, especially over white, may necessitate a second coat to prevent the underlying color from showing through.
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Sheen and Surface Smoothness: The sheen of the existing paint surface is discussed as a factor influencing the number of coats. High-sheen surfaces may cause the new paint to "slide," leaving streaks that require additional coats. This demonstrates an understanding of how surface smoothness affects paint adhesion.
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Paint Grade and Solids Content: The grade of paint is highlighted as a factor influencing the number of coats, with premium paints containing higher volumes of solids. This aligns with the knowledge that paints with more solids deposit more material, enhancing coverage and potentially eliminating the need for a second coat.
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Application Methods: The article explores different application methods, including brushes, rollers, and spraying. It explains how each method has implications for the number of coats required. The preference for certain methods in specific situations reflects a practical understanding of the challenges associated with each.
In conclusion, the depth of knowledge demonstrated in the article, combined with practical insights, establishes a solid foundation for making informed decisions in painting projects.
